某新型无人帆船的结构设计及其主帆结构的轻量化设计

对为了满足海洋调查长航时、大范围和连续性的调查要求,研发了一款带有襟翼的刚性帆无人帆船,同时为了优化其帆形和结构,对主帆结构进行轻量化设计。将Fluent软件计算得到的气动载荷施加到主帆表面,结合ANSYS Workbench软件提出了形状-拓扑-尺寸联合分级优化的方法,通过形状优化,确定了主帆外形为锥形。通过拓扑优化,建立了薄蒙皮、“工”字形翼梁和桁架式肋板的主帆结构模型,对其初始模型进行有限元分析,结果表明初始主帆符合设计要求,并且其结构有很大优化空间。利用响应面分析法,确定主帆蒙皮厚度和翼梁宽度两个参数对主帆结构性能和质量影响较大。通过对主帆结构进行尺寸优化,最终确定蒙皮厚度为2.8mm,翼梁厚度为3mm,翼梁宽度为26.5mm,肋板厚度为2mm。优化后的主帆结构满足设计要求,质量减轻了38.68%。

基于ANSYS Workbench的卡簧压装机轻量化设计及其压头的疲劳分析与优化

为满足卡簧压装机的经济性要求与可靠性要求,验证其机身和压头结构设计的合理性,避免机身出现安全系数过高和压头发生疲劳破坏的问题。运用ANSYS Workbench对机身和压头进行静力学分析,确定最大变形量和最大应力的结构位置。通过静力学分析得到机身结构存在较大的优化空间,利用拓扑优化,对机身进行去除材料的形状优化,达到轻量化的设计要求。通过对压头进行疲劳分析,得到压头损伤因子为0.93。为提高卡簧压装机的可靠性,通过设置正交试验,将压头圆形通孔、压头爪的厚度和宽度进行参数化建模,建立了疲劳寿命函数的优化数学模型,通过MATLAB优化工具箱计算出优化后的参数值。最后,将优化后的机身与压头重新进行有限元分析,其机身质量减轻了23.5%,压头疲劳寿命提高了1.7倍。

Experimental Investigation of the Resistance Performance and Heave and Pitch Motions of Ice-Going Container Ship Under Pack Ice Conditions

In order to analyze the ice-going ship’s performance under the pack ice conditions, synthetic ice was introduced into a towing tank. A barrier using floating cylinder in the towing tank was designed to carry out the resistance experiment. The test results indicated that the encountering frequency between the ship model and the pack ice shifts towards a high-velocity point as the concentration of the pack ice increases, and this encountering frequency creates an unstable region of the resistance, and the unstable region shifts to the higher speed with the increasing concentration. The results also showed that for the same speed points, the ratio of the pack ice resistance to the open water resistance increases with the increasing concentration, and for the same concentrations, this ratio decreases as the speed increases. Motion characteristics showed that the mean value of the heave motion increases as the speed increases, and the pitch motion tends to increase with the increasing speed. In addition, the total resistance of the fullscale was predicted.

Numerical Simulation on the Resistance Performance of Ice-Going Container Ship Under Brash Ice Conditions

Ice resistance prediction is a critical issue in the preliminary design of ships navigating brash ice conditions, which is closely related to the safety of a ship to navigate encounter brash ice, and has significant effects on the kinds of propellers and motor power needed. In research on this topic, model tests and full-scale tests on ships have thus far been the primary approaches. In recent years, the application of the finite element method(FEM) has also attracted interest. Some researchers have conducted numerical simulations on ship–ice interactions using the fluid–structure interaction(FSI) method. This study used this method to predict and analyze the resistance of an ice-going ship, and compared the results with those of model ship tests conducted in a towing tank with synthetic ice to discuss the feasibility of the FEM. A numerical simulation and experimental methods were used to predict the brash ice resistance of an ice-going container ship model in a condition with three concentrations of brash ice(60%, 80%, and 90%). A comparison of the results yielded satisfactory agreement between the numerical simulation and the experiments in terms of both observed phenomena and resistance values, indicating that the proposed numerical simulation has significant potential for use in related studies in the future.

无人帆船的翼帆气动性能研究

为了促进无人帆船在海洋调查等方面的应用,对一种无人帆船的刚性翼帆进行了气动性能研究。首先,对翼帆模型进行参数化建模,运用Fluent软件的SST模型对其进行CFD分析,得出襟翼位置、展弦比、锥度比和倾斜角对翼帆气动性能的影响规律。其襟翼距离主帆较近时会减小翼帆的升力系数,襟翼上下位置对翼帆的升力系数不产生影响;主帆采用大展弦比会提高翼帆气动性能,其次,采用锥形主帆,当锥度比τ=0.45时,可以降低主帆重心和根部的弯曲载荷,同时翼帆仍具有较好的气动性能;随着主帆倾斜角度的增加,翼帆气动中心降低、升力系数减小。